1. Field of the Invention
The invention relates to methods for shortening CSFB performance time.
2. Description of the Related Art
The evolution of wireless communication technologies often requires that newer systems and networks be compatible with existing systems and networks. A communication specification defining the operation of new technology often provides requirements for the new system to interface with these legacy systems. For example, the 3GPP Long term Evolution (LIE) standard requires that a wireless communication device be able to use circuit switched networks for voice calls as well as utilizing the LTE network. For example, LTE allows a circuit switched fall back (CSFB) procedure, in which an LTE handset can leverage the existing infrastructure of previous 2G or 3G technologies to make or receive voice calls. In other words, the LTE handset can drop an existing LTE connection with an LTE evolved Node B (eNB) and fall back to a 2G or 3G cell (e.g., Node B or base station). During the CSFB procedure, the LTE session is suspended. Upon completion of the call, the LTE handset can then re-establish a connection with the LTE network.
However, when performing CSFB, long delay times usually occur. A long delay time can be frustrating for the user and contribute to a high failure rate in establishing voice calls.
Therefore, a method for shortening CSFB delays is highly required.